Fire-alarm



(No Model.) T. SHAW.

FIRE ALARM.

No. 243,984. Patented July 5, 1881.

WITNESSES: Q J INVENTORO a MM M W a/wuwd UNITED STATES PATENT OF CE.

THOMAS SHAW, or PHILADELPHIA, PENNSYLVANIA.

FIRE-ALARM.

SPECIFICATION forming part of Letters Patent No. 243,984, dated July 5, 1881. Application filed May 16, 1881. (No model.)

To all whom it may concern .3

Be it known that I, THOMAS SHAW, of the city and county ofPhiladelphia, Pennsylvania, have invented a new and Improved Process of Automatically Detecting Undesirable Fires over Large Areas ot'Buildings, Sheds, 8m; and I hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawing, and to the letters of reference marked thereon.

My invention relates to that class of firealarms in which a combustible cord, when burned, serves as ameans ot'creatiug an alarm; and my invention is a simple, cheap, and effective apparatus, whereby the alarm is given when tension is removed from the cord. v

The drawing-shows the improved device, (1 being the cord, which is attached at one end, i, to a wall or other object, and k a weight suspended from the other end.

The alarm is of any suitable character, as a train of wheels and gong, a whistle, cartridge, or any of the well-known devices, which is set, Wound up, or otherwise prepared for operation, and is held in action by a detent consisting of a spring-plate, g, attached at one end to a block, a, the other end affording a bearing for a lug, which may be on a disk, 0, upon a shaft of the gear-train, or upon any other part of the alarm mechanism, so that when the plate 9 is moved from the lug the train will be set in operation and sound an alarm.

The tendency of the spring is to withdraw the plate from the lug; but the rope (I, passing over a pulley, 6, supported between ears on the plate, so long as it supports the weight 70, serves to draw out the plate to the position shown, a pin, 71., in the plate, passing through a hole in the block a, and provided with a head or enlargement, serving as a means of limiting the outward movement of the plate. The rope'is conducted to those points where it will be most likely to be burned should a fire occur, and as soon as it is thus severed all draft upon the plate will be removed, and it will spring back, releasing the alarm mechanism.

To secure a signal to a distant point the plate 9 may connect with an electric wire, m, and an electrode, f, connects with another, and is arranged so that the circuit is complete when the plate and electrode are in contact, and a current transmitted to an electric alarm.

I claim- 1. The combination, in a fire-alarm, of an alarm device, substantially as described, a spring-plate, g, arranged as a detent for the alarm device, and a cord, (1, connected to the plate, as specified, to hold it in position so long as the cord is taut, substantially as set forth.

2. The combination" of alarm mechanism, spring-detent plate g, carrying a roller, 0, and weight z', as set forth.

3. The combination of the alarm mechanism, spring-detent plate g, roller 0, cord, weight Ia, electrodef, and wires 1 m, as specified.

THOMAS SHAWV.

Witnesses:

T. FRANK MILLER, WM. GARWOOD. 

